The iPhone 3GS AND the iPhone 4 will now cost you NOTHING if you sign up to certain contracts with some of the UK's top networks.
The iPhone 3GS
The lowest monthly contracts are currently offered by Orange and Three, who both offer you an iPhone 3GS handset for only £20 a month. Obviously it might make sense to not go straight for the cheap as chips option as you don't get much data or many unlimited texts and calls, you'll also probably have to sign up for a 24 month contract too. However, it is pretty cool that you can now get your hands on an iPhone device for just £20 a month.
The iPhone 4
The iPhone 3GS isn't the only device which you can now get for free, all of the same networks are also offering the iPhone 4 free, depending on which contract you sign up for. It seems most require you to commit to an 18 month or 24 month contract and pay over £40 a month to get an iPhone 4 for nothing.